Fourteen stream segments were investigated throughout the Xin’an Spring in Shanxi Province, China in 2004. The variation ranges in stream size, current velocity, discharge, dissolved oxygen, and specific conductance were large. Twenty-two macroalgae species were found in the stream. Major divisions in terms of species numbers were Chlorophyta (59.1%), Cyanophyta (22.8%), Xanthophyta (9.1%), Rhodophyta (4.5%) and Charophyta (4.5%). The most widespread species, Cladophora rivularis (50.0%), also Oedogonium sp. (42.9%) and Spirogyra sp. (42.9%) were well represented throughout the stream, whereas another 10 species were found in only one sampling site. Total percentage cover varied from <1% to 90%. Red algae Batrachospermum acuatum and the charophytes Chara vulgaris have the highest percentage cover. Among the parameters analyzed, the stream width, specific conductance and dissolved oxygen were the ones that more closely related to the species number and percentage cover of macroalgal communities. The species number of each site was negatively correlated with dissolved oxygen content. The total percentage cover of the macroalgae was negatively correlated with the stream width and the specific conductance. 相似文献
A cruise through the western sea area of the Taiwan Strait was carried out by the R/VDong Fang Hong in December, 1987. Eight anchored and 10 not anchored stations were set up. Over 25 time-series current observations were
made at each station and CTD (Conductivity-temperature-depth) measurements were made at 5 anchored and 10 not anchored stations.
Based on the measured data. fine-structures and step-like vertical structures of temperature and salinity were analysed and
a tentative wintertime current structure in the Taiwan Strait was described. 相似文献
The geological condition may vary largely from one support to another for a long span bridge. The effect of geological variability and spatial variation produced by propagation and coherence loss of seismic ground motion on the response of long span suspension bridges is investigated in this article. The case of Jiangyin Yangtse River Bridge, a suspension bridge with a main span of 1385 m, is studied in detail. Numerical results show that the geological difference at the supports has a significant effect on the seismic response of long span suspension bridges and, that it is unacceptable to neglect the difference. The effect of the propagation of seismic ground motion on the response of long span suspension bridges is far more important than that of the coherence loss. The response of bridges varies greatly with the horizontal apparent velocity in a very complex way, and there is a critical horizontal velocity for a given response quantity. 相似文献
In the processes of discrimination between oil-cracked gases and kerogen-cracked gases, Behar and Pinzgofer et al.’s results were adopted in the former researches, in which the ratio of C2/C3 is basically a constant while the ratio of C1/C2 gradually increases in the course of primary cracking of kerogen. Otherwise in the course of secondary cracking of oil, the ratio of C2/C3 increases rapidly while C1/C2 keeps relatively stable. Our study on analogue experiment shows that, whether it is oil or kerogen, in its process of gas generating by cracking, the ratios of C2/C3, C1/C2 or C1/C3 will all be increased with the growth of thermal conditions. In comparison, the ratio of C2/C3, which is affected by genetic type to some comparatively less extent, mainly responds to the maturity of gases, while the value of C2/C3 is about 2, and that of C2/iC4 is about 10, and the corresponding value of Ro is about 1.5%–1.6%. The influence of gas source on C2/C3 is less than that of gas maturity, otherwise C1/C2 (or C1/C3) is obviously affected by cracking matrices. The ratios of C1/C2, C1/C3 of oil-cracked gases are less than that of kerogen-cracked gases, under the condition that the ratios of C2/C3 are similar in value, so are the value of dryness indexes. There exists wide diffidence between this view and the former discrimination method in theory. The analysis of the spot sample indicates that we can apply the above basic view to dealing efficiently with the problem of the discrimination between oil-cracked gas and kerogen-cracked gas.
After the earthquake (Ms = 6.1) occurred in Luquan county of Yunnan province on April 18, 1985, the relationship between major
earthquakes and astronomical time-latitude residuals (ATLR) of a photoelectric astrolabe in Yunnan Observatory was analyzed.
ATLR are the rest after deducting the effects of Earth’s whole motion from the observations of time and latitude. It was found
that there appeared the anomalies of the ATLR before earthquakes which happened in and around Yunnan, a seismic active region.
The reason of the anomalies is possibly from change of the plumb line due to the motion of the groundmass before earthquakes.
Afterwards, using studies of the anomalous characters and laws of ATLR, we tried to provide the warning information prior
to the occurrence of a few major earthquakes in the region. The significant synchronous anomalies of ATLR of the observatory
appeared before the earthquake of magnitude 6.2 in Dayao county of Yunnan province, on July 21, 2003. It has been again verified
that the anomalies possibly provide the prediction information for strong earthquakes around the observatory. 相似文献